1. Field of the Invention
The present invention relates to an image communicating system such as a facsimile apparatus or the like which can transmit and/or receive image data.
2. Description of the Prior Art
Generally, facsimile apparatuses are constituted by: a reading system for optically reading the content of an original to be transmitted and converting to an electrical signal; a recording system for hard-copying by a printer or the like on the basis of the received signal or the like; and a controller for controlling the reading and recording systems.
As a recording system of the facsimile apparatus using a subscriber's telephone line, in general, there has conventionally been used the recording system having a thermal printer using a thermal paper. The thermal printer, however, has a drawback such that the printing speed is slow although it has advantageously a high resolution.
Therefore, in the facsimile apparatuses using subscriber's telephone lines, the recording apparatus having a high resolution and a high enough printing speed is demanded.
To improve both the resolution and the printing speed, there is considered a method whereby a reception memory to store the received data is provided and when a predetermined amount of data (for example, data of one page) has been stored in the reception memory, this data is transmitted to the printer.
On one hand, in the facsimile apparatus, there is considered another method whereby when data has once been received, the same content as this data is multicopied by printing it onto a plurality of print papers. In this case, it is necessary to use a dedicated memory (retention memory) to store the read data or received content.
Further, in the facsimile apparatus, there is considered a method whereby the broadcasting transmitting function to transmit the same data as the read data of an image to other plurality of facsimile apparatuses by a single operation is provided. In this case, it is necessary to use a dedicated memory (memory for broadcasting transmission) to store the read data.
As mentioned above, a reception image memory is needed to print the received image at a high speed, a retention memory is needed to obtain a plurality of recording images from a single image, and a broadcasting transmission memory is needed for the broadcasting transmission.
Namely, a memory of a large capacity is necessary to obtain a high-speed facsimile apparatus with multifunction.
It is assumed that when the facsimile apparatus on the transmission side reads an image data with a high resolution and the pixel density in the main scanning direction is 16 pels/mm and the scanning line density in the subscanning direction is 15.4 lines/mm, those of the facsimile apparatus on the reception side are, for example, 8 pels/mm.times.7.7 lines/mm or 4 pels/mm.times.3.85 lines/mm. In this case, since the number of pixels to be transmitted is too large, the received image is magnified in the apparatus on the reception side, so that the whole image cannot be fully printed on a recording paper and the printer becomes the unrecordable state.
On the contrary, in the case where the apparatus on the transmission side reads an image data with a low resolution and the apparatus on the reception side records this image data with a high resolution, the number of pixels transmitted is so small that the size of image data transmitted is reduced and this image data is recorded by the printer on the reception side, so that there is a drawback such that a picture quality of the received image deteriorates.